The present invention relates to catheter components and, more particularly, to such components formed of a compound of polymer with particles or fibers.
Cathethers used to treat, e.g., blocked arteries in coronary, peripheral, and neurovascular fields are typically guided to a treatment site by riding over a guidewire. Although the guidewire is sometimes coated with a friction-reducing material such as TEFLON, there is generally some friction when a plastic catheter is pushed over the wire.
In the past, in balloon catheters, polyethylene was used as the balloon material in the catheter. This allowed the use of low friction, High Density Polyethylene (HDPE) as the lumen for the guidewire. A low profile heat bond could be performed at the distal tip of the balloon and the guidewire lumen to allow for a smooth transition and a soft tip.
As more advanced and stronger materials have been developed for the balloon, such as Polyester (PET), Nylon, and Acrylon (Acrylonitrile), a need for an alternative to HDPE has arisen. HDPE as a single material cannot be heat bonded to materials such as Polyester, Nylon, and Acrylon. Some of the materials that can be bonded to Nylon balloons include Polyether Block Amide (PEBAX) and Nylon, however, these materials tend to have higher surface friction than HDPE. One solution has been to coextrude an inner layer of HDPE or TEFLON and an outer layer of some other material, such as PEBAX. This is more costly than an HDPE extrusion, and the coextrusion can result in delamination. Alternatively, an adhesive bond has been used. However, adhesive bonds tend to be undesirably stiff and have a relatively high profile.
Materials with low surface friction such as HDPE, and various fluoropolymers such as PolyTetraFluoroEthylene (PTFE) (also known as TEFLON as manufactured by DuPont), TetraFluorEthylene-Perfluorpropylene (FEP), and PerFluoroAlkoxy (PFA), cannot be heat bonded to many modern balloon materials and are difficult to process. Materials presently used as the guidewire lumen for Nylon balloons are commonly Polyether Block Amide (PEBAX), Nylon 11, Nylon 12, or blends of these materials. Materials used for PET and Acrylon balloons are Hytrel and PET/Polyurethane blends. Polyurethane balloons used for neuro applications also commonly use polyurethane or PEBAX inner wire lumens. All of these materials have high surface frictions at body temperature and have the potential to interfere with guidewire movement.
It is desirable to provide a material suitable for use in a catheter having a low surface friction and that is flexible and easy to process. It is particularly desirable to provide such a material for use in connection with a guidewire lumen.
In accordance with an aspect of the present invention, a guidewire lumen for a catheter comprises a tubular member. At least a portion of the tubular member is formed of a compound comprising a polymer and between about 2-15% particles or fibers by weight.
In accordance with another aspect of the present invention, a catheter comprises a guidewire lumen comprising a tubular member, at least a portion of which tubular member formed of a compound comprising a polymer and particles or fibers. The catheter further comprises a catheter component bonded to the portion of the guidewire lumen without adhesive. A bond strength of a bond between the catheter component and the portion of the guidewire lumen is no more than 10% less than a bond strength of a bond between a second catheter component substantially identical to the catheter component and a portion of a second guidewire lumen substantially identical to the guidewire lumen and formed of the polymer without particles or fibers.
In accordance with yet another aspect of the present invention, a method of making a catheter comprises forming a compound comprising a polymer and between about 2-15% particles or fibers by weight, forming a tubular extrusion of the compound, and bonding the tubular extrusion to a catheter component.
In accordance with yet another aspect of the present invention, a guidewire lumen for a catheter comprises a tubular member. At least a portion of the tubular member is formed of a compound comprising a polymer and particles or fibers. The portion of the tubular member has a coefficient of friction at least 10% lower than a substantially identical tubular member formed of the polymer without the particles or fibers.
In accordance with yet another aspect of the present invention, a tubular catheter component comprises PEBAX compounded with about 2-15% graphite particles, wherein the graphite particles have sizes of about 1-15 μm.